The fact is, we don’t know much about that and there are too many variables to be able to test this properly.

What we know for sure:

Social media mentions (i.e. links in them) are used for URL discovery. I’ve seen it millions of times. You create a new website and a new page on it. Then you wait for it to be discovered (with no luck as you have no backlinks yet!). They you tweet that page and you find it soon being in the indexed!

Google Plus mentions will definitely effect the personalized SERPs of your Google Plus friends. Whenever you search (while being logged in into Google Plus), you’ll see “results plussed by your friends” here and there by default.

What we seem to be pretty sure about:

Google is making its best to incorporate social in ranking (that’s why Google Plus was born) but it is failing for now (otherwise, backlink paranoia would have been killed already). Google is making its best social media “signals” are already being incorporated, not yet clear how though.

From the thread itself:

The current orthodox belief is to claim that Google evaluates your site’s broad online presence, and social media plays some part in it: it confirms to Google that yours is an authority site. This sounds about right. Nothing more specific can be said about social media’s use in rankings at this stage.

My personal experience suggests that the impact of social media on organic Google rankings is minimal at best, though it may well increase in the future. I observe many sites closely, and I have not found that launching a social media campaign for a site and carrying it on for months visibly increases a site’s rankings.

I think social signals have minimal effect on SERPs for the time being.If it did play a major role in rankings, then it would surely put in vain the efforts of link building…even in future the scope of these signals for SEO will be limited to Google + subscribers.

I don’t want to buy into this yet. I’ll probably want it to not happen, too. If social media is to be considered a ranking factor, even just around 1-2% of the algorithm, that could spell real trouble – imagine how many blackhats can easily game this! Just my two cents.

I’ve been puzzling over the link between social media and SEO for a while… this tells me that there definitely might be something to it! We should all probably focus a little more on the social media aspect.